The best thing about this announcement is that when Maverick ships, we should have turbo boost drivers working on the Z9PE and other dual Xeon E5 builds.
These builds already get Geekbench 28000+, should be blowing the new Mac Pro out of the water when the new chips come out (2x 12 core chips anyone?).
No PCIe means that this machine doesn't deserve to be called a Mac Pro. Thunderbolt V2 is 20Gbps each way, the latest PCIe is 10x faster (31GBps).
Also a dual processor machine has double the PCIe data lines, another reason that this will be a relatively weak and non-upgradable machine.
I will definitely be sticking with my Z9PE, twice as good for half the price I bet (and should be compatible with Xeon E5 V2 26xx chips).
plenty of working builds are at other sites.